1. Field of the Invention
This invention relates to a ribbon shield for use with a ribbon cassette in a printer. More particularly, this invention relates to a ribbon shield for use in a ribbon cassette of the type which contains an endless loop of inked ribbon and which is used in a wire matrix printer.
2. Description of the Prior Art
The use of some type of shield to prevent the smudging or wicking of ink from a ribbon onto a paper in a printing machine is well known. Such shields are disclosed in U.S. Pat. Nos. 398,837 to Loker Jr., 532,211 to Nichols, 733,851 to Koch, 760,371 to Baker, 2,409,237 to Banks and 3,017,981 to Keith. These ribbon shields all perform generally the same function in that they isolate all but a small portion of an inked ribbon from the paper carried in a printing machine such as a typewriter. In the above patents, the ribbon shield is a permanent part of the printing apparatus itself. Therefore, it is subject to the build-up of ink deposits and may require frequent cleanings in order to properly perform its function. In order to alleviate this problem, recent printers which utilize a cassette for carrying the inked ribbon have incorporated a ribbon shield into the cassette rather than the printer mechanism. The shield is thus replaced each time a new ribbon cassette is inserted into the machine. Such ribbon cassettes having integral ribbon shields are disclosed in U.S. Pat. Nos. 3,643,777 to Anderson et al, 3,980,171 to Frechette and 3,941,231 to Matuck. The Matuck patent is directed specifically to a ribbon cartridge for use with a wire matrix printer. In each of these patents, the ribbon shield is secured in a fixed position with respect to the ribbon cartridge. The ribbon shield includes a small opening through which a portion of the ribbon can be forced to accomplish printing.